1. Field of the Invention
The invention relates to a chipset, and in particular, to a chipset with a redundant array of independent disks (RAID).
2. Description of the Related Art
To provide large volume, high read/write performance or security, redundant arrays of independent disks (RAID) are commonly utilized. RAID systems allow storage of the same data in different places (redundantly) on multiple disks. A number of disks are arranged in a disk array, referred as a disk set, and data is distributed in different places for improved data security. Moreover, the data can be partitioned into several segments and stored in different disks, allowing input/output operations to overlap in a balanced way, improving performance. In addition, by using a parity check, the RAID can read data on the disk array even if any one of the disks in the disk array is damaged.
FIG. 1 shows an embodiment of a computer system 100. The computer system 100 includes a RAID 130, a Southbridge 108, a Northbridge 104, a system memory 106 and a central processing unit 102. As shown in FIG. 1, it is assumed that the RAID 130 includes three disks 132, 134 and 136. The Southbridge 108 includes a disk controller 110 controlling storage to disks 132, 134 and 136. The Northbridge 104 is coupled among the Southbridge 108, the system memory 106 and the central processing unit 102.
As shown in FIG. 1, the disk controller 110 may be an integrated driver electronic (IDE) controller or an advanced host controller (AHC). The system memory 106 may be a dynamic random access memory (DRAM).
FIG. 2 is a flowchart showing the conventional method for performing RAID write. The central processing unit 102 firstly writes Data D1 to the system memory 106 (step S201). Then, the disk controller 110 reads data D2 from the disk 134 and writes the data D2 to the system memory 106 (step S202). Accordingly, the central processing unit 102 performs an exclusive OR (XOR) logical operation on data D1 and D2 to obtain a parity data DP (step S204). Next, the central processing unit 102 writes the parity data DP to the system memory 106 (step S205). Then, the disk controller 110 writes the data D1 to the disk 132 (step S206). Finally, the disk controller 110 writes the parity data DP to the disk 136 (step S207).
As noted, the central processing unit 106, however, handles most of the steps while performing RAID write, resulting in poor performance of the computer system.